Doing the Moon Spruce Hustle

Photo by Iler Stoe on Unsplash

In my efforts to teach myself how to build guitars my academy of choice has been YouTube. This astonishingly rich resource has also taught me how to dismantle and service my dishwasher, how to recharge the freon in my van’s air conditioning system… I’m pretty sure that if I needed to self-perform an emergency appendectomy I could find a YouTube cut and slice tutorial.

That said, there is also no shortage of poor methodology and Calaveras County sized frog whoppers to be found on YouTube. I found a particularly fun tall tale on Michael Watts’ YouTube channel, one that is cherished among the luthiers and musicians who favor hand-built and custom stringed instruments.

Michael Watts is a wonderful finger style guitarist, and whenever I need a mood boost I watch one of his guitar review or performance videos. On one such video from a year ago he discussed the origins and supposed virtues of “Moon Spruce”, which commands a premium price from both builders and eventual buyers of custom guitars. This supposedly superior tone wood gets its name from the method of its harvest, which is carefully tuned to the season and the phase of the moon.

Photo by John Ruddock on Unsplash

Watts’ descriptions echo the wood tales that have floated around the lutherie community for decades touting the superiority of winter harvested wood. Not only must “moon spruce” be cut in the winter and on a waning quarter moon, it also must be felled with the crown down the hill, and left with branches attached for a period of time so that the sap will run into them, supposedly leaving the wood dryer and sap free .

This sounds like a difficult routine, one that a tree harvester would only contemplate if it rendered better quality timber. For the traditional woods workers of Stradivarius’ time who produced the original moon spruce, the opposite was actually true.

Promoters of moon spruce do mention that the necessary harvest method mirrors traditional woods work practices that go back centuries; what they fail to mention is that those guys with two-man whip saws and horse teams weren’t dumb. The truth is that centuries ago, when workers used hand tools and muscle power to move their logs down from the high mountains, winter tree harvest was orders of magnitude easier than summer harvest and was the norm.

To understand this visualize two mountain lovers, one a skier and the other a hiker, who both bust an ankle up on the mountain and need rescue. A ski patroller takes care of the skier, helps them onto a taboggan, and slides them down to the aid shack at the bottom of the hill. This takes about ten minutes. The hiker, on the other hand, needs to be hand carried off the mountain, and even though the stretcher they ride is far lighter than the taboggan, it takes two to four strong bodies and several hours to finish the rescue.

The litter carriers have to fight their way through the thorny brush, over rocks and deadfall logs, and have to carry all the weight to make any progress, slapping mosquitoes and trying not to twist their own ankles in the process. The ski patroller just needs to control the load which slides freely over the snow and carries its own weight.

The same dynamic holds true for every phase of hand moving loads over broken country. Winter snow fills in the uneven and obstacle strewn terrain, covers the deadfall logs and half buried boulders, and a trail tramped into the snow pack quickly becomes an icy chute. Whether tree sections were slid down off of the slopes, or skidded through the forest behind a horse team, snowpack eliminated the need to hand cut trails smooth and wide enough for dragging or toting heavy loads… in winter the biggest job would be to keep a load from sliding too fast.

Photo by Andrea Stark on Unsplash

Felling the tree with the crown down the hill was no special deal, it was then and still is standard operating practice. Only a foolish tree faller aims the toppling tree up the hill unless there is no alternative, and in that case he might just pass the tree by. Live spruce weighs over thirty pounds a cubic foot, a tree large enough to yield good instrument wood can easily weigh fifteen thousand pounds. When you release that much potential energy to the grip of gravity you do NOT stand downslope from it…it might choose to bounce or slide further down the hill, it’s not going to jump back up at you.

And as for the sap running out of the wood and into those downhill branches, the sap doesn’t run through the heartwood that you are seeking in the first place. Trees have three general regions, the bark and cambium layers that carry most of the water and nutrients to the leaves or needles, the sap wood which is still alive and open to fluid transport, and inside, the heart wood, which has died and in which the valves that allow fluid to flow have closed.

Photo by Markus Winkler on Unsplash

Given that the sap was not stored in or flowing through the spruce heartwood and so could not run from there into the branches, the moon spruce winter felling procedures would make little difference to the quality of the wood. When the harvest job in front of the woods workers is considered however, the March moving date makes perfect sense. As avid skiers will attest, the snowpack is deepest around March when the slopes have “filled in”, with obstacles that might have grabbed your ski or ripped off your edges in December now deeply buried.

Once again, those guys weren’t dumb, and they knew the easiest and most efficient ways to do their work. The work day was shortest in December and January, the snow pack was thinnest, and the temperatures were the coldest. While they may well have wanted to get a head start on felling trees, they naturally would have waited until conditions were prime to move them. Waiting too much after March to skid their products out of the forest got increasingly risky. The minute the spring thaw began that snowpack highway started to shrink, the snow itself turned punky and slushy, and a muddy morass was not far behind.

Luthiers want spruce from the heartwood of mature trees, tone wood harvesters want to take mature trees with as much clear heartwood as possible, to make their labors worth the while. Spruce is a specialty wood, great for soundboards on stringed instruments and not good for much else. The weight to strength ratio of spruce wood is first rate, the strength to volume ratio isn’t. Its ability to flex and rebound makes it ideal to convert string vibrations into sound waves, but also makes it undesirable for construction…imagine how annoying a floor that bounces and vibrates underfoot would be.

Photo by Leo Fosdal on Unsplash

The best quality European spruce trees grew at altitudes of 6000 feet of elevation or higher. Trees for construction lumber, similar to Douglas fir in the U.S., could be found at lower elevations, and with old growth forests not yet decimated by the chain saw, the mobile yarder, and the log truck, could presumably be found closer to the traditional logger’s home lumber yard. With a limited and very picky market for instrument quality trees, and with the greater effort needed to procure superior trees, those timber harvesters would have made every effort to take them as efficiently as possible.

The last piece of the woods worker’s puzzle was processing the harvested logs for drying and sale. The luthier wants radial sections, cut like pie wedges from bark to core. In addition they want these sections to be split rather than sawed to prevent the bane of “runout”. Each tree has an obvious grain, the growth rings around the bullseye of the core, and a hidden grain, the path that the wood fibers themselves take up the trunk.

One dry rail has a spiral grain path, the other straight up the trunk

Sometimes the fibers grow straight up the trunk, sometimes they spiral to the left or the right. Only by splitting a short log section, or “round”, can you align the resulting wedge with the path the fibers have taken, and if this step has been skipped, a plane blade or sharp chisel will follow the fibers, “running out’ at an angle to the blank being worked.

While mill workers of the day had some capacity to “rip saw” pieces lengthwise, the standard practice was to hand split and hew the logs along their length. This was done when the wood was wet, or “green”, and easy to work. Doing this heavy labor with wedges and splitting mauls is far more pleasant in cold weather. It’s easy to wear mittens or gloves, to add another coat if the temps are low, it’s dangerous to do this work while scantily clad in order to survive the toil in the broiling summer sun. And of course, it’s dumb to move more wood out of the forest and back to your lumber yard than you can sell.

So, we have moon spruce explanations that make little scientific sense, and we have the standard traditional logging practices that amply explain all the supposed required harvest methods…except of course that lunar timing that is namesake to the product. This is where I think the tall tales come in.

Decades ago I worked with a salty old character harvesting spruce for stringed instruments. Tom was both a brilliant tool maker and heavy load mover, and a font of categorical knowledge about forests and tree species. He was also known to stretch the truth from time to time. I don’t know for certain that he didn’t catch and bag rattlesnakes out of his wood pile and then release them in front of startled tourists at scenic overlooks, maybe he was telling me the gospel truth. But one way or the other, someone’s leg was being pulled.

I don’t know for certain that the phases of the winter moon can’t have some effect on living trees. I am pretty sure that the kind of rough characters who could fell a huge tree on a snowy December slope, horse it down to flat ground, buck it up into four-foot lengths and split those lengths with wedges and a ten-pound sledge, might just pull the leg of a clean handed and apron wearing luthier. All the more likely if doing so would bump the price up a skosh;)

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